Depression

The Cytochrome P450 Genetic Test

Over the past decade, the study of human genetics has shown how genetic factors influence a person's response to medications and their side effects. Mayo Clinic psychiatrists and laboratory medicine specialists developed a blood test (cytochrome P450) to pinpoint genetic factors that play a role in a person's response to various drugs, including most antidepressant medications. The test represents a major advance in providing the most appropriate depression drug treatment to meet each patient's needs.

The cytochrome P450 blood test provides information on how a person's body metabolizes (breaks down) drugs. Genes are contained in each of the body's cells. They instruct the body to produce proteins that control how cells grow and function. This test identifies the gene or genes responsible for producing enzymes to metabolize these drugs.

Certain patients may metabolize an antidepressant slowly. This can cause side effects or a toxic reaction, which may lead the patient to stop taking the drug. Others may metabolize the drug quickly, eliminating it from the body before they benefit from it. The cytochrome P450 test gives the doctor additional information to help choose the right antidepressant and the correct dose to reduce side effects for each patient.